Knurling apparatus



Aug. 10, 1965 J. L. LYELL KNURLING APPARATUS 2 Sheets-Sheet l Filed Aug. 15

Aug. 10, 1965 J. L. LYELL 3,199,325

KNURLING APPARATUS Filed Aug. 15, 1962 2 Sheets-Sheet 2 ATTORNEYS United States Patent 3,199,325 KNURLING APPARATUS John L. Lyell, Shelby/ville, Mo. Filed Aug. 15, 1962, Ser. No. 217,172 6 Claims. (Cl. 72-74) This invention relates to knurling apparatus and more particularly to such apparatus especially adapted for knurling pistons of internal combustion engines.

As is well known in the art, worn pistons can be rendered suitable for further service by raising the outer surface of the piston skirt. This is accomplished by knurling the skirt at least on the opposite thrust areas of the piston which are positioned at the opposite sides of the piston pin.

While knurling devices are available to perform this function, nevertheless they are for the most part expensive, bulky and cumbersome. Devices of simpler form are dllfiCllli to use since they require k-nurling of the two thrust areas of the piston in separate operations and often require dis-assembly of the piston pin and connecting rod from the piston proper.

With these considerations in mind, it is the principal purpose and object of the present invention to provide improved piston knurling devices which are of relatively simplified construction and yet which effect the knurling of the two piston thrust areas simultaneously without requiring dis-assembly of the piston and piston rod.

It is also an object of the present invention to provide improved knurling devices which are compact and rugged and which may be manufactured and sold at a price which permits their use in relatively small garages and machine shops.

It is an additional object of the present invention to provide improved knurling devices which may be easily set up for use and operated by mechanics of limited skill and training.

It is also an object of the present invention to provide improved knurling devices which may be readily adjusted to accommodate pistons of widely differing diameter and length.

Additional objects and advantages will become apparent as the description proceeds in connection with the accompanying drawings in which:

FIGURE 1 is a top plan view of a preferred embodiment of the knurling device constructed in accordance with the present invention;

FIGURES 2 and 3 are side elevations of the apparatus, FIGURE 3 showing the piston installed for knurling; and

FIGURE 4 is a top plan view showing the knurling tools removed from the remainder of the apparatus.

Referring now more particularly to the drawings, the

knurling apparatus of the present invention is supported on a rectangular base 20 which, if desired, may be provided with holes to permit firm attachment of the base to a suitable table or other work surface. Secured by any suitable means to opposite ends of the base 20 are a pair of upwardly projecting parallel cylindrical rods 22 and 24 which support the knurling assembly per se indicated generally at 26 and a piston holder assembly indicated generally at 28. The assembly 26 includes a main bracket member 30 having a ring portion 32 from the opposite sides of which project mounting bosses 33 and 34 provided with bores through which the respective rods 22 and 24 extend with a close sliding fit. The inner periph- 3 ,1 ,3 2 5 Patented Aug. 10, 1965 cry of the portion 32 of bracket 39 is provided with stepped bores 35 and 36 which rotatably receive the outer peripheral stepped machined surfaces of a ring 38, the upper and lower surfaces of which are substantially flush with the upper and lower surfaces of the ring por tion 32.

An annular plate 42 is rigidly secured, for example as by screws 40, to the lower surface of the ring. Thus the assembly comprising the ring 38 and the plate 42 may freely rotate with respect to the bracket 39 but are held against vertical movement with respect to the bracket 3%).

Formed integrally with diametrically opposed portions of the plate 32 are parallel, downwardly projecting bosses 44 and 46 which support the knurling frame assembly 26 shown separately in FIGURE 4. This assembly comprises a pair of identical bars 48 and 5t) adjustably connected by threaded shafts '52 and 54, the shaft 52 being rigid with the bar 50 and extending freely through the bar 48 and the shaft 54 being rigid with the bar 48 and extending freely through the bar 55 Thus the distance between the bars 48 and 5%) may be adjusted by tightening or loosening nuts 5-6 and S8 threaded onto the outer projecting ends of the bars 52 and 54, respectively.

The bar 48 carries a relatively fixed knurling assembly indicated generally at 60 and the bar 50 carries an adjustable knurling assembly indicated generally at 62. The assembly 6t) comprises a thimble or operating handle 64 rigidly secured to or threaded onto a shaft 66 extending through the bar 48 and supporting on its inner end a carrier 68 on which a hardened steel knurl '70 is rotatably supported by a pin 72. The assembly is held in fixed position by a nut 74.

The opposite adjustable knurl assembly 62 comprises a sleeve 76 threaded into the bar 54 and having a central smooth bore 78 through which the shaft 8d of a knurl carrier 82 slidably extends. A hardened steel knurl 84 is rotatably supported on a pin 86 mounted on the carrier 82 which is also provided with a laterally projecting boss 83 through which a guide pin 90 threaded into the bar 50 extends to prevent rotation of the carrier 82 on its shaft 80.

The outer end of the shaft is threaded as at 92 and extends into a similarly threaded portion of the operat ing thimble 94 which is also threaded onto the outer end of the fixed sleeve 76. The threads on the sleeve '76 and the threads on the shaft 80 are of different pitch and of opposite hand and are preferably so arranged that one full rotation of the thimble 94 will advance or retract the knurl 8d .050 inches.

When the knurling assembly 25 is installed, the shafts 52 and 54 slide freely in the bosses 4d and 46. Accordingly, any adjustment of the thimble 94 produces a symmetrical adjustment of the knurls 7t and S4 with respect to the axis of the piston.

The piston holder assembly 23 comprises an elongated bar 96 the ends of which are provided with bosses through which the support rods 22 and 24 extend. The bar fifi may be clamped at any adjusted height on the shafts 22 and 24 by clamp members 9% and W0. A central boss M2 on the bar d6 has a central opening into which a vertical shaft 104 is adjustably threaded. Rotatably mounted on the lower end of the shaft MM is a disc 1% having a lower conical surface 198 which wedgingly engages the upper end of the piston skirt as shown in FIG- URE 3.

A notch 110 is provided at one side of the disc 106 to accommodate the connecting rod. The journal portion of the connecting rod and the bearing cap are held in fixed position by a clamp assembly carried by the arm 96. The clamp assembly comprises an arm 112 adjustably carried by an L-shaped bracket 114 adjustably secured to the arm 6 by a stud and nut 116. The outer end of the arm 112 carries a threaded shaft 118 on which a clamp member 120 is loosely positioned. The spacing between the clamp member 12% and the outer end of the arm 112 may be adjusted by operation of the knob 122. The entire clamp assembly may be laterally shifted by movement of the stud and nut 116 in the elongated slot 123 in the arm 96.

In use, the piston to be treated is installed head down as shown in FIGURE 3 with the center of the head in engagement with the spring loaded centering detent 124 carried in a central boss 130 in the base 20. If necessary the clamps 98 and 100 are loosened to permit adjustment of the holding assembly 28 to the proper height. Then the centering plate 106 is brought down into firm engagement with the upper edge of the piston skirt. The shaft 118 of the clamping assembly is removed, the bar 112 is properly positioned, the shaft is re-installed extending through the bearing portion of the connecting rod and this portion of the connecting rod is then firmly clamped between the members 112 and 120 by operation of the knob 122. When these preliminary operations have been completed, the entire piston and connecting rod assembly are held firmly in fixed position and the axis of the piston is automatically positioned symmetrically of the apparatus.

Two adjustable stops 132 and 134 are then suitably positioned on the rod 24 and clamped in adjusted position by tightening the screws 136 and 138. The stops 132 and 134 are so positioned as to establish and limit the vertical travel of the knurling apparatus to the appropriate portion of the piston skirt. If necessary the spacing of the bars 48 and 50 is adjusted to bring the knurls roughly to the desired spacing. The thimble 94 is then adjusted to bring the knurls 70 and 84 into proper pressure engagement with the opposite thrust areas of the piston. As noted above, the contact pressure between the two knurls and the piston skirt will be equal because of the lateral float of the knurling support assembly 26. Preferably the thimble 94 and the shaft 76 will carry suitable indicia of the type generally employed in micrometers in order that exact repeat operations may be performed.

The knurling operation is then performed by oscillating the thimbles 64 and 94. The are through which the knurls may be oscillated is limited by stops 140 and 142 which are screwed into one of a series of suitably spaced tapped openings 144 provided in the upper surface of the ring 38. At their limit of travel, the stops 140 and 142 contact a fixed stop member 146 carried by the upper surface ring portion 32 of the member 30. The proper placement of the screws 14% and 142 assures the knurling of symmetrical areas of equal circumferential extent on each of the sides of the piston.

The knurling operation is started with the bracket 30 in its uppermost position as shown in FIGURE 2. Then as the knurling tools are oscillated, the entire bracket 30 slides down the shafts 22 and 24 until the knurling is completed when the lower stop 134 is reached.

From the foregoing it will be apparent that the above stated objects of the invention have been achieved by the provision of relatively simple, easy to use rugged mechanism for knurling equal patterns of any desired height and circumferential extent on the opposite thrust surfaces of the piston without dis-assembling the piston from the associated connecting rod and pistonpin.

The invention may be embodied in other specific forms without departing from the spirit or essential characterismay be readily accommodated by substituting an appropriately shaped clamp for the disc 1% and by positioning an adaptor on the base 20. The present embodiment is I therefore to be considered in all respects as illustrative and not restrictive, the scope of the invention being indicated by the appended claims rather than by the foregoing description, and all changes which come within the meaning and range of equivalency of the claims are there fore intended to be embraced therein.

What is claimed and desired to be secured by United States Letters Patent is:

1. Apparatus for simultaneously knurling opposed portions of a piston comprising a base, means for holding said piston in predetermined fixed position on said base, a bracket mounted on said base for movement toward and away from said base, a support member carried by said bracket for rotation about the axis of said piston, said support member having a pair of parallel through bores at opposite sides of the axis of rotation of said support member, a frame assembly having parallel shafts extending freely through said bores whereby said frame assembly rotates with said support member but may float laterally with respect thereto in the direction of said shafts, and a pair of diametrically opposed knurls carried by opposite end portions of said frame assembly for engagement with diametrically opposed surfaces of said piston, the diameter connecting said surfaces of said piston being parallel to said shafts.

2. Apparatus for simultaneously knurling opposed pore tions of a piston comprising, a base for supporting one end of said piston, shaft means rigid with said 'base and extending upwardly therefrom, a centering member having a surface engageable with the opposite end of said piston, means adjustably supporting said centering member on the upper portion of said shaft means for movement toward and away from said base, a bracket supported on said shaft means for movement toward and away from said base, an annular support member rotatably carried by said bracket in surrounding relation with said piston, said s pport member having a pair of parallel through bores at opposite sides of the axis of rotation of said support member, a frame assembly having parallel shafts extending freely through said bores whereby said frame assembly rotates with said support member but may float laterally with respect thereto in the direction of said shafts, and a pair of knurls carried by said frame assembly at diametrically opposed points with respect to said piston and'engageable with opposed portions of said piston, the line connecting said knurls being essentially parallel to said shafts.

3. The apparatus according to claim 2 together with cooperating stop means on said bracket and said support member for limiting the rotation of said support member with respect to said bracket.

4. The apparatus according to claim 3 together with stop means on said shaft means for limiting the movement of said bracket with respect to said base.

5. Apparatus for simultaneously knurling opposed portions of a piston comprising a base, mcans for holding said piston in predetermined fixed position on said base, a bracket mounted on said base for movement toward and away from said base, an annular support member carried by said bracket for rotation about the axis of said piston, said support member having a pair of parallel through bores at opposite sides of the axis of rotation of said support member, a pair of frame members, a knurl carried by each of said frame members, a pair of parallel shafts adjustably connecting said frame members, said shafts extending freely through said bores whereby said shafts, said frame members and said knurls rotate with said support member but may float laterally with respect thereto.

6. Apparatus for simultaneously knurling opposed por- References Cited by the Examiner tions of a piston comprising, a base, means for holding UNITED STATES PATENTS sa1d piston in predetermmed fixed position on said base, a bracket mounted on said base for movement toward 1,414,668 5/22 Reed and away from said base, a support member carried by 5 1,984,155 12/34 Prochilska' 8051 said bracket for rotation about the axis of said piston, a 2,798,390 7/57 Banned 80-51 frame, a pair of opposed knuriers carried by said frame 219451406 7/60 Moore at opposite sides of the axis of said pistons, and means FOREIGN PATENTS mounting said frame on said support member for rota- 704,749 5/31 France tion therewith and for free floating movement in a direc- 10 tion parallel to a diameter connecting said opposed piston CHARLES W LANHAM Primary Examiner portions. 

1. APPARATUS FOR SIMULTANEOUSLY KNURLING OPPOSED PORTIONS OF A PISTON COMPRISING A BASE, MEANS FOR HOLDING SAID PISTON IN PREDETERMINED FIXED POSITION ON SAID BASE, A BRACKET MOUNTED ON SAID BASE FOR MOVEMENT TOWARD AND AWAY FROM SAID BASE, A SUPPORT MEMBER CARRIED BY SAID BRACKET FOR ROTATION ABOUT THE AXIS OF SAID PISTON, SAID SUPPORT MEMBER HAVING A PAIR OF PARALLEL THROUGH BORES AT OPPOSITE SIDES OF THE AXIS OF ROTATION OF SAID SUPPORT MEMBER, A FRAME ASSEMBLYY HAVING PARALLEL SHAFTS EXTENDING FREELY THROUGH SAID BORES WHEREBY SAID FRAME ASSEMBLY ROTATES WITH SAID SUPPORT MEMBER BUT MAY FLOAT LATERALLY WITH RESPECT THERETO IN THE DIRECTION OF SAID SHAFTS, AND A PAIR OF DIAMETRICALLY OPPOSED KNURLS CARRIED BY OPPOSITE END PORTIONS OF SAID FRAME ASSEMBLY FOR ENGAGEMENT WITH DIAMETRICALLY OPPOSED SURFACES OF SAID PISTON, THE DIAMETER CONNECTING SAID SURFACES OF SID PISTON BEING PARALLEL TO SAID SHAFTS. 